1. Field of the Invention
The present invention generally relates to tools, and more specifically to a high energy permanent magnet magnetizer and a demagnetizer for magnetizing and/or demagnetizing a magnetizable element such as a driver bit, a fastener, and the like, for driving tools.
2. Description of the Prior Art
It is frequently desirable to magnetize the tips of screwdriver bits, tweezers and the like to form at least a temporary magnetic pole magnetizable elements. Thus particularly with precision screwdrivers which tend to be relatively small and are used to drive relatively small head screws, it is frequently advantageous to at least temporarily magnetize the screwdriver tips of the driver bits to maintain the screwdriver blade or tip within the slot of a screw head or within the cross slots formed within the head of the screw adapted to receive the Phillips screwdriver tip. By magnetizing the tip of the driver bit, and mating screw head, the screw remains attached to the bit tip without the need to physically hold them together. This allows the screw to be guided through a relatively small bore or channel and moved within a confined space. Sometimes the magnetized tip of the driver bit is used to retrieve a metal item, such as a screw, washer, nail or the like, from an inaccessible place which would otherwise be difficult to reach with anything but a relatively thin shank of a driver bit. Of course, such attachment of a fastener to the driver bit tip also frees the user""s hand for holding or positioning the work into which the fastener is to be driven. In some instances, rather than magnetizing the tip of the driver member bit, the fastener itself is magnetized so that, again, it is attracted to and remains magnetically attached to the driver bit tip in the same way as if the latter had been magnetized.
Conversely, there are instances in which a magnetized driver bit tip is disadvantageous, because it undesirably attracts and attaches to itself various magnetizable elements or components. Under such circumstances, it may be desirable to demagnetize a driver bit tip that had been originally magnetized in order to render same magnetically neutral.
Devices for magnetizing/demagnetizing tools and small parts are well known. These normally incorporate one or more permanent magnets which create a sufficiently high magnetic field to magnetize at least a portion of a magnetizable element brought into its field. The body can be magnetized by bringing it into the magnetic field. While the magnetic properties of all materials make them respondent in some way to magnetic fields, most materials are diamagnetic or paramagnetic and show almost no response to magnetic fields. However, a magnetizable element made of a ferromagnetic material readily responds to a magnetic field and becomes, at least temporarily, magnetized when placed in such a magnetic field.
Magnetic materials are classified as soft or hard according to the ease of magnetization. Soft materials are used as devices in which change in the magnetization during operation is desirable, sometimes rapidly, as in AC generators and transformers. Hard materials are used to supply fixed fields either to act alone, as in a magnetic separator, or interact with others, as in loudspeakers, electronic instruments and test equipment.
Most magnetizers/demagnetizers include commercial magnets which are formed of either Alnico or of ceramic materials. The driver members/fasteners, on the other hand, are normally made of soft materials which are readily magnetized but more easily lose their magnetization, such as by being drawn over an iron or steel surface, subjected to a demagnetizing influence such as strong electromagnetic fields or other permanent magnetic fields, severe mechanical shock or extreme temperature variations.
One example of a stand alone magnetizer/demagnetizer is magnetizer/demagnetizer Model No. 40010, made in Germany by Wiha. This unit consists of a plastic box that has two adjacent openings defined by three spaced transverse portions. Magnets are placed within the transverse portions to provide magnetic fields in each of the two openings which are directed in substantially opposing directions. Therefore, when a magnetizable tool bit or any magnetizable component is placed within one of the openings, it becomes magnetized and when placed in the other of the openings, it becomes demagnetized. The demagnetizing window is provided with progressive steps to stepwise decrease the air gap for the demagnetizing field and, therefore, provides different levels of strengths of the demagnetizing field. However, common magnetic materials that are used with conventional magnetizers/demagnetizers include Alnico and ceramic magnets which typically have energy products equal to approximately 4.5xc3x97106 gauss-oersteds and 2.2xc3x97106 gauss-oersteds, respectively.
Since the magnetic field strength xe2x80x9cBxe2x80x9d at the pole of the magnet is a product of the unit field strength and the area, it follows that the energy content is proportional to the BH product of the magnet. The BH product is a quantity of importance for a permanent magnet and is probably the best single xe2x80x9cfigure of meritxe2x80x9d or criterion for judging the quality of the permanent magnetic material. It is for this reason that conventional magnetizers/demagnetizers have required significant volumes of magnetic material to provide the desired energy content suitable for magnetizing and demagnetizing parts. However, the required volumes have rendered it impossible or impractical to incorporate the magnetizers/demagnetizers on relatively small hand tools. Thus, for example, precision screwdrivers, which are relatively small and have relatively small diameter handles, could not possibly incorporate sufficient magnetic material to provide desired levels of magnetic fields for magnetizing and demagnetizing parts. However, the requirement of using separate magnetizer/demagnetizer units has rendered their use less practical. Thus, unless the user of a precision screwdriver or any driver tool acquired a separate magnetizer/demagnetizer, one would not normally be available for use. Additionally, even if such magnetizer/demagnetizer were available, it would still require a separate component that could be misplaced and not be available when needed. Additionally, there is always the risk that the magnetizer/demagnetizer could become misplaced or lost, rendering the use of the driver tool less useful.
Another problem with prior art magnetizers/demagnetizers is that they fail to address the problem that during demagnetization the element being demagnetized may be either insufficiently demagnetized or overly demagnetized to effectively re-magnetize the element with opposing polarity. Thus, prior art magnetizers/demagnetizers have failed to consider the importance of the strengths of the magnets and the sizes of the elements being magnetized and demagnetized. Thus, typically, the larger the element, the more magnetic field required to demagnetize it. However, demagnetization of all sized elements within the same field may result in some elements being insufficiently demagnetized, while others become overly demagnetized. In either case, the end result is unsatisfactory in that an element which was intended to be demagnetized continues to exhibit magnetic poles and generate a magnetic field.
Prior applications Ser. Nos. 09/161,851 and 09/161,855 involved high energy magnetizer/demagnetizers related to driver tools that described inventive magnetizer/demagnetize features for engagement of the driving tip of a driver tool with a fastener such as a Phillips head screw and inventive provision for the placement of the magnetized element in a suitable demagnetizing field.
Neither of these inventions, however, provided a magnetizer/demagnetizer unit for magnetizing and demagnetizing driver tool bits that in addition provides for magnetizing a fastening element, or elements, such as a Phillips screw or screws, and for holding or storing the same magnetized element, or elements, on an opposing magnetic field of the same magnetizer/demagnetizer unit, so that the user can transport the e.g. driver tool with the magnetized unit to a work area and then remove the stored magnetized screw or screws for driving the magnetized screw or screws into the work object.
It is an object of the present invention to provide a high energy magnetizer/demagnetizer for a driving tool bit that also includes a magnetized area for holding a magnetizable fastening element or elements such as a screw or screws for transportation of the same to or holding same at a work area.
It is another object of the present invention to provide a magnetizer/demagnetizer as aforementioned which provides sufficiently strong magnetic fields to effectively and adequately magnetize/demagnetize a driver bit of the driving tool while also providing a magnetized holding area for storing the fastening element or elements by magnetic attraction to a work area.
It is still another object of the present invention to provide a magnetizer/demagnetizer as in the previous objects in which the magnetizer/demagnetizer including the magnetized holding area is a stand-alone unit that is adherently attached to a non-operative portion of the driving tool or other useful surface.
It is yet another object of the present invention to provide a magnetizer/demagnetizer as in the previous objects that includes the magnetized holding area that is unitary or integral with a non-operative portion of the driving tool.
It is yet another object of the present invention to provide a magnetizer/demagnetizer as in the previous objects that includes a magnetized holding area for holding a fastening element or elements such as a screw or screws wherein the magnet is an elongate magnet, or bar magnet, that provides a sufficient holding area that can hold at least one screw by magnetic attraction.
It is yet another object of the present invention to provide a magnetizer/demagnetizer as in the previous objects that includes a magnetized holding area for holding a fastening element of elements such as a screw or screws wherein the magnet is a composite super magnet and a magnetizable elongated shunt magnetized by the super magnet, such as a steel shunt, wherein the shunt provides a sufficient holding area than can store at least one fastening element or a plurality of fastening elements by magnetic attraction.
It is yet another object of the present invention to provide an elongated, or bar, magnetizer/demagnetizer which uses a permanent magnetic material having an energy product equal to at least 7.0xc3x97106 gauss-oersteds.
The magnetizer/demagnetizer of the present invention may be alternatively secured to, in addition to driver tool housings, other useful metallic and non-metallic surfaces, which by way of example include, the top of a ladder, adjacent a work area, a tool box cover and the user""s work belt.
In order to achieve the above objects, as well as others which will become apparent hereinafter, there is provided a high energy magnetizer/demagnetizer in combination with a power driving tool including a magnetizable tool bit for driving the head of a fastening device or the like comprising an elongated permanent magnet having opposed first and second poles arranged on a non-operative portion of the driving tool or the like to permit placement of a magnetizable tool bit on the elongated magnet at the first position associated with the first pole to magnetize the tool bit and also to permit placement of the tool bit at a second position associated with the second pole to demagnetize the tool bit, the second position being at a predetermined distance from the magnet. The elongated magnet defines a holding area to permit placement of at least one fastening device at a third position on the elongated magnet associated with the second pole. The fastening device is held at the third position by magnetic force and can then be carried with the driving tool to a work area where the magnetized fastener and the oppositely charged tool bit are connected during the work. Mounting means holds the elongated magnet and provides first and third accesses at the first and third positions, respectively, to the elongated magnet and for provides the predetermined distance at the second position. The elongated magnet can be either a single elongated high energy magnet or can comprises a high energy magnet portion and an elongated shunt portion. The magnetizer/demagnetizer is either separately attached to the housing of the power tool or is unitary with the housing.
As will be evident from the discussion of FIG. 18, the magnetic force required to magnetize a magnetizable material is significantly greater than the magnetic force required to demagnetize that material. A feature of the invention is the arrangement of the magnet herein in such a way that the demagnetizing of a driver tool bit is accomplished at the predetermined distance from the magnet so that the demagnetizing force is less than the magnetizing force. While the predetermined distance is not critical, it should be selected to generally correspond to the magnetizing and demagnetizing forces required to magnetize and to demagnetize a driver tool bit. The magnetizing and demagnetizing forces are a function both of the size of the driver tool bit and also the material from which driver tool bit is made. The material of both driver tool bit and also the screw is significant as is evident from FIG. 18, where the it is shown that different materials show different magnetic properties, requiring different magnetic intensities or magnetizing forces to produce the same magnitudes of magnetic field or magnetic flux. The dimensions of the material to be magnetized and demagnetized are also important, because the more volume that the driver tool bit and the screw each have, the greater the magnetic field that will be required, since what is instrumental in magnetizing and demagnetizing the material is not only the absolute intensity of the magnetic field but also the relative density of the field taken across a given cross-sectional area of the tool, screw, that is, the magnetizable material.